Polish Academy of Sciences, Institute of Oceanology, Department of Marine Chemistry, and Biochemistry, ul. Powstańców Warszawy 55, 81-712 Sopot, Poland.
University of Gdansk, Faculty of Oceanography and Geography Laboratory of Marine Plankton Biology, Division of Marine Biology and Biotechnology, Al. Piłsudskiego 46, 81-378 Gdynia, Poland.
Sci Total Environ. 2023 Dec 20;905:167239. doi: 10.1016/j.scitotenv.2023.167239. Epub 2023 Sep 22.
The Antarctic is the most isolated region in the world; nevertheless, it has not avoided the negative impact of human activity, including the inflow of toxic mercury (Hg). Hg deposited in the Antarctic marine environment can be bioavailable and accumulate in the food web, reaching elevated concentrations in high-trophic-level biota, especially if methylated. Zooplankton, together with phytoplankton, are critical for the transport of pollutants, including Hg to higher trophic levels. For the Southern Ocean ecosystem, one of the key zooplankton components is the Antarctic krill Euphausia superba, the smaller euphausiid Thysanoessa macrura, and the amphipod Themisto gaudichaudii - a crucial food source for most predatory fish, birds, and mammals. The main goal of this study was to determine the Hg burden, as well as the distribution of different Hg forms, in these dominant Antarctic planktonic crustaceans. The results showed that the highest concentrations of Hg were found in T. gaudichaudii, a typically predatory taxon. Most of the Hg in the tested crustaceans was labile and potentially bioavailable for planktivorous organisms, with the most dangerous methylmercury (MeHg) accounting for an average of 16 % of the total mercury. Elevated Hg concentrations were observed close to the land, which is influenced by the proximity to penguin and pinniped colonies. In areas near the shore, volcanic activity might be a possible cause of the increase in mercury sulfide (HgS) content. The total Hg concentration increased with the trophic position and ontogenetic stage of predation, specific to adult organisms. In contrast, the proportion of MeHg decreased with age, indicating more efficient demethylation or elimination. The Hg magnification kinetics in the study area were relatively high, which may be related to climate-change induced alterations of the Antarctic ecosystem: additional food sources and reshaped trophic structure.
南极洲是世界上最孤立的地区；然而，它也未能避免人类活动的负面影响，包括有毒汞（Hg）的流入。沉积在南极海洋环境中的 Hg 可以具有生物可利用性，并在食物网中积累，在高营养级生物中达到较高浓度，特别是在被甲基化的情况下。浮游动物与浮游植物一起，对于污染物（包括 Hg）向更高营养级的运输至关重要。对于南大洋生态系统，关键的浮游动物组成部分之一是南极磷虾 Euphausia superba、较小的磷虾 Thysanoessa macrura 和端足目动物 Themisto gaudichaudii——这是大多数捕食性鱼类、鸟类和哺乳动物的关键食物来源。本研究的主要目的是确定这些主要南极浮游甲壳类动物中的 Hg 负荷以及不同 Hg 形态的分布。研究结果表明，Hg 浓度最高的是 T. gaudichaudii，这是一种典型的捕食性生物。在所测试的甲壳类动物中，大部分 Hg 是不稳定的，对浮游生物具有潜在的生物可利用性，最危险的甲基汞（MeHg）平均占总汞的 16%。在靠近陆地的地方观察到了升高的 Hg 浓度，这受到了靠近企鹅和鳍足类动物聚居地的影响。在靠近海岸的地区，火山活动可能是汞硫化物（HgS）含量增加的一个可能原因。总 Hg 浓度随着捕食的营养位置和个体发育阶段的增加而增加，这是特定于成年生物的。相比之下，MeHg 的比例随着年龄的增加而降低，这表明更有效的去甲基化或消除。研究区域的 Hg 放大动力学相对较高，这可能与气候变化引起的南极生态系统改变有关：增加了食物来源和改变了营养结构。
